From the Profootball Hall of fame's webpage
"The date was November 12, 1892, a day that would forever be etched in sports history, although no one involved that day could possibly have recognized the importance of the occasion. It was the day that the Allegheny Athletic Association football team defeated the Pittsburgh Athletic Club. The game in itself was not a momentous event. But one of the circumstances of the game did make it a never-to-be-forgotten moment in sports history – one of the AAA players, William (Pudge) Heffelfinger, was openly paid $500 to play the game. Thus pro football made its debut more than 100 years ago in comparatively obscure surroundings that could not possibly have provided the slightest clue to the world-wide popularity the sport would be destined to enjoy, particularly in the waning decades of pro football's first century."